Hi Andrew.
Actually the "Add Member" and "Remove Member" buttons are implemented listing all the queues associated to a user following this order:
1. All assigned: a composed queue formed by all queues where the agent is working on;
2. All elementary queues where the agent is working on;
3. All other elementary queues visible by the agent.
The idea we had, when we implemented this strategy, was to let able agents to log-in/out to queues not directly assigned to them, for example, to help queues with temporary problems.
Filtering out elementary queues, as asked in your post, requires some modifications in the QueueMetrics code.
We track your suggestion in our feedback tracker as #688 and we plan to implement it in future QueueMetrics releases.
Thank you for your feedback.
Regards,
Marco.